Yesterday Reginald Crew, 74, from Liverpool, ended his own life with a lethal drink of barbiturates in a flat in Zurich. Mr Crew, who suffered from motor neurone disease, was forced to seek help abroad because British law does not recognise the right to die.

Last year, Diane Pretty's courageous fight through UK and European courts saw two clear opinions emerge on whether we allow terminally ill adults in the UK the choice of requesting medical help to die. In one camp, the government repeatedly stated that it had no intention of changing the law for fear of abuse. On the other hand, public opinion polls before, during and after the case repeatedly showed that more than 80% of the public supported Diane's battle for a change in the law.

With the ruling against Diane Pretty, the government may have felt by retaining the status quo the vulnerable would be protected. Yet the growth of a very disturbing phenomenon - so called "death tourism" has quite clearly shaken this belief to the core.

The Voluntary Euthanasia Society hears from desperate terminally ill adults and their families on a daily basis. They are forced to consider taking drastic measures because the law in the UK prevents them from requesting a good death. As a result, many people, including Mr Crew, have contacted the Swiss organisation Dignitas, which assists adults to commit suicide.

It is of immense public concern that people with terminal illnesses are forced to travel to a foreign country to end their days, in unfamiliar surroundings, and without proper safeguards in place.

Furthermore, if friends and families accompany them, they are confronted with the added burden of not knowing if they will face prosecution on their return to the UK. In the short term, the director of public prosecutions can and should publish a policy as a matter of urgency so these people know their legal rights.

This policy is not a long term solution. We have repeatedly warned the government that Dignitas is just the tip of the iceberg.

The government has no idea how many vulnerable people are being helped to die either in Britain or abroad. It has commissioned no research into clandestine assisted dying and so does not know the extent of the problem. What is clear is that our laws are failing to prevent "back-street suicide" - people are helped to die in the UK even though it is against the law.

In most cases, relatives who assist their loved ones to die never come before the courts. The few who do inevitably receive suspended sentences. But by that time, who knows if dying was what the person themselves really wanted?

Relatives are certainly not the best people to assist. They lack the medical knowledge to guarantee a peaceful death, and failed suicide attempts cause further suffering. Accounts of relatives who try to assist paint a worrying picture - many try to take their own lives afterwards due to the understandable psychological strain.

Additionally, it is well known that some members of the medical profession in the UK will actively help their patients to die out of compassion, but without legal guidance or second or third opinions. Doctors can dramatically increase doses of painkillers towards the end of a person's life so long as their stated intention is only to relieve their patient's suffering. Others will be more upfront about their actions but will again be compelled to act in secret and without guidelines because of the legal position.

On Monday, as Mr Crew was being helped to die in Switzerland, we received a call from someone in the UK who explained that their doctor had recently helped one of their parents to die at their request.

This regularity of this type of act is confirmed by a survey of UK doctors published in 1998 in which 15% of doctors admitted to helping a patient to die at their own request. And in 1996, a British Medical Association survey discovered 3% of GPs and hospital doctors had actively ended the lives of terminally ill patients on their request.

If the government intends to continue denying people such as Diane Pretty the legal choice of asking for medical help to die, it must at least defend its stance with hard facts. What research there is suggests that leaving people to seek help in secret creates serious problems, which need to be addressed through transparency and regulation.

In the Netherlands and Belgium, assisted dying for the terminally ill is allowed, but it is strictly regulated. Legal safeguards mean doctors will not assist people from other countries. For starters, there has to be a long-term relationship between the patient and the doctor so that the doctor can explore all possible alternatives.

It is no coincidence that Belgium and the Netherlands are the only two European countries to date to have conducted proper research into assisted dying. Both found that without regulation the vulnerable had inadequate protection while terminally ill adults were denied their basic human right to die with dignity. They acted and changed their laws.

There is also an urgent need to protect the vulnerable from back-street assisted suicide at home and abroad, and offer people such as Diane Pretty, who are mentally competent and terminally ill, the option of a safe, legal, medically assisted death here in the UK. Continuing the cruelty is indefensible if it is based on misinformation and unfounded concerns.

· Deborah Annetts is chief executive of the Voluntary Euthanasia Society